The present invention relates to process variable transmitters of the type used to measure process variables in industrial processes. More specifically, the present invention relates to verification of operation of such process variable transmitters.
Process variable transmitters are used in industrial processes to measure process variables such as pressure, temperature, flow, etc. These measurements can be used to monitor operation of the industrial process. In some configurations, the industrial process is controlled based upon the measured process variables.
In some types of industrial processes, such as industrial processes which are subjected to regulations (for example, pharmaceutical or food manufacturing processes), there are regulations which require that proper operation of the process variable transmitters be periodically verified. For example, for a transmitter which measures flow of process fluid, an operator may periodically be required to place a known quantity of process fluid through the sensor of the flow transmitter and compare the output of the flow transmitter with the actual amount (known) amount of flow. The operator typically manually calculates the error and logs the data in a written log book.
Another example technique used to verify operation of a process variable transmitter is to compare the process variable output of the transmitter with the process variable output of a reference process variable transmitter. Again, the error must be manually calculated and manually recorded in a log book.